Lets take a look at the Difference Between Primary and Secondary Wastewater Treatment
Depending on the location of your property and local Council regulations, you may need Primary and Secondary Wastewater Treatment. Water treatment processes are essential for protecting both public health and the environment.
Both primary and secondary treatment are designed to remove solids, organic matter, and some pathogens from wastewater before it is released or reused. Advanced treatment, including tertiary treatment and nutrient removal, may be used to further improve water quality and protect sensitive aquatic species.
These processes transform contaminated water into a form that is safe for discharge or reuse, meeting environmental and health standards. Advanced treatment steps ensure the final effluent meets strict standards for discharge or reuse, supporting the health of aquatic species and sensitive ecosystems.
Firstly what is wastewater?
Wastewater is any water that has been used and contaminated by human activity, whether it comes from households, businesses, or industrial facilities. This includes water from sinks, toilets, showers, washing machines, and even industrial processes. Because this water contains a mix of organic matter, chemicals, and other pollutants, it cannot be released back into the environment without proper treatment.
Wastewater treatment is a vital process that protects our waterways, public health, and the environment. The main goal of the wastewater treatment process is to remove contaminants and produce treated water that is safe for discharge or reuse. One of the most important stages in this process is secondary treatment, also known as biological treatment.
During secondary treatment, biological processes are used to break down organic matter and further reduce pollutants, ensuring that the treated water meets strict environmental and health standards before it is released or reused.
By using a combination of physical, chemical, and biological treatment steps, modern wastewater treatment plants are able to transform contaminated water into treated water that supports healthy ecosystems and communities.
Where does wastewater come from?
Wastewater is the used water from toilets, showers, baths, kitchen sinks, laundries and industrial processes. Around 99% of wastewater is water, and the other 1% is contaminating waste and solids.
Wastewater can come from any of the following places :
- Shops
- Homes
- Farms
- Factories
- Offices
- Restaurants
- Public Toilets
- Aged Care Facilities
- Medical Facilities
- Fuel and transport depots
- Quarries
- Mines
Wastewater generated from factories and industrial facilities is often called industrial waste or trade waste. This type of wastewater contains pollutants that require specialized sewage treatment processes before being discharged, to protect water quality and public health.
Types of wastewater
Domestic - Residential Wastewater
Water that comes from kitchen sinks, showers, toilets, baths and laundries in your office or home
Industrial - Business Wastewater
This water comes from industrial and manufacturing plants, such as a food processing. This can also include water that has some alternative purposes, such as water to clean or cool machinery.
Industrial wastewater is typically treated at a sewage treatment plant or specialised treatment plant to remove harmful substances before the water is released or reused.
Preliminary Treatment Steps
Before wastewater can undergo primary and secondary treatment, it first passes through preliminary treatment steps designed to protect the treatment system and improve overall efficiency. These initial steps focus on removing large debris and materials that could damage equipment or interfere with later treatment processes.
Preliminary treatment typically begins with screening, where large objects like sticks, rags, and plastics are filtered out. Next, grit removal tanks allow heavier particles such as sand and small stones to settle out. These steps are crucial for preventing blockages and wear in pumps and pipes throughout the wastewater system.
After preliminary treatment, the wastewater moves into primary treatment works, where the primary process allows solids to settle and lighter materials to float. The resulting liquid then enters the secondary pre-treatment chamber, where anaerobic bacteria begin breaking down organic matter. This prepares the wastewater for the next stage: secondary treatment.
In secondary treatment, advanced biological processes such as trickling filters or the activated sludge process are used to further remove organic pollutants. These systems rely on microorganisms to digest and break down remaining contaminants, resulting in treated water that is much cleaner and safer for the environment.
By carefully managing each step of the treatment process, from preliminary screening to biological treatment, wastewater treatment plants ensure that both the remaining solids and dissolved pollutants are effectively removed, protecting water quality and supporting sustainable water management.
We thought it also valuable to mention Stormwater
Stormwater is a type of wastewater that runs off various areas, such as roofs, gardens, roads, paths and gutters. This water flows into stormwater drains, especially after it rains, can flow straight into our waterways untreated.
This water needs to keep away from transportation areas.
What is Primary Treatment?
Primary wastewater treatment is the process of removing solid matter from wastewater. The wastewater flows into tanks and the suspended solids settle on the bottom and require retention time. The grease and scum then rise to the top.
This is a very slow process. The primary process is also called the ‘primary phase’ or the ‘septic process’. Septic tanks are a common form of on-site primary treatment, especially in rural or low-density areas. Primary treatment often relies on natural processes to separate solids from wastewater.
The lighter wastewater and matter then leave and go to the secondary pre-treatment chamber. The anaerobic bacteria (bacteria that does not need oxygen to live) uses the nasties in the water as food and they begin to break them down.
What is Secondary Treatment?
The secondary wastewater treatment process, also known as secondary sewage treatment, uses anaerobic microorganisms and retention time to break down and remove the remaining waste and other small particles. The waste and the microorganisms are both found in the sludge, and remove both the remaining solids and nutrients through bacterial composition.
Secondary treatment systems, also referred to as secondary wastewater treatment systems, use a biological process to remove organic matter and achieve nutrient removal from wastewater. Secondary treatment utilises naturally occurring biological processes to remove organic matter and improve water quality.
This means the wastewater oxygen level varies throughout and does not stay at one constant quantity. This results in microorganisms being either aerobic (require oxygen) or anaerobic (does not require oxygen), depending on the stage.
Anaerobic processes, in contrast to aerobic ones, play a significant role in sludge digestion and the removal of organic material, helping to reduce sludge volume and manage waste efficiently during treatment. These systems require air blowers running for a long time to reinvigorate and aerate the liquids.
So what is the difference between Primary and Secondary Wastewater Treatment?
The main difference is the way each respective treatment is processed. Primary treatment works on sedimentation, where solids separate from the water through several different tanks. In contrast, secondary treatment uses aeration, biofiltration and the interaction of waste throughout its process.
Both primary and secondary treatment are integral components of larger treatment systems, wastewater treatment systems, and wastewater systems designed to protect the environment.
There are various disposal options for the solids and sludge generated during primary and secondary treatment, including land application, incineration, composting, and landfill, depending on site conditions and regulatory requirements.
Primary Treatment
- This process generally utilises mechanical equipment to breakup larger particles
- In primary treatment larger particles are removed
- Slow
- The primary wastewater treatment utilises filtration and sedimentation processes
Secondary Treatment
- Secondary treatment uses biological processes for extraction
- With secondary wastewater treatment smaller particles are removed
- Slower
- The secondary treatment uses anaerobic or aerobic breakdown processes
Consider the Worm Farm Wastewater Treatment System
This powerful organic wastewater treatment system effectively processes sewage, all household wastewater and organic waste. It includes food and vegetation, as well as some weeds. As part of its sludge treatment process, the system uses anaerobic digestion to break down organic matter, producing biogas and reducing sludge volume.
The results are a treated effluent that is suitable for reuse, such as irrigation or groundwater recharge. Combined with naturally occurring organisms, the worm liquid opens up and improves the quality of your soil.
This allows you to reuse and recycle it as liquid fertiliser under your garden, lawns and bush land. Independently tested the Worm Farm Waste System is super fast at processing sewage, wastewater and organic waste. In fact 20 times faster than any normal septic system.
If you need Primary or Secondary Wastewater Treatment it can be easily achieved with the Worm Farm Waste System
Here’s Why Over 3600 Aussie's Choose Our Truly Wastewater Treatment System
- Established in 1996
- Over 3600 systems installed in Australia
- Secondary Wastewater Treatment Certified
- Single chamber with low site impact
- Low power consumption approximately $180 per year
- Residential & Commercial systems
- We help with Council Permit Applications - ‘We talk council speak’
- No Service Contracts
- No smells
- Approved in VIC, NSW, SA, QLD & NT
- 10 Year System Warranty
- Operates 20 times faster than septic or aerated systems in processing sewage solids
- Our pumps are very quiet & only activated by demand
- Suitable for all climates, desert, tropical, alpine and temperate
- Company employed installers are used to install your system
- Environmentally friendly and sustainable
- Natural liquid fertiliser is added into your soil, opening up clay soils 100mm vertically per year
- Can reduce household organic waste by up to 90%
- Many site specific effluent dispersal options
- Aerobic system with a wind driven vent pipe
All our residential systems come with a Child Proof Entry